This project is devoted to surface x-ray scattering studies of epitaxial growth onto perfect crystal substrates. Part of the effort will be devoted to an extension of exact results of dynamical diffraction theory to surface diffraction, to complement current descriptions based on kinematical theory. Measurements will be made on clean silicon and germanium surfaces in ultra-high vacuum using the triple crystal diffraction (TCD) method. Experiments will then proceed with monolayer coverages of lattice- matched alkali halides epitaxially grown onto Ge surfaces, with both TCD and x-ray standing wave (XSW) measurements being used to solve the "phase problem." The studies will also be extended to thicker layers of alkali halides, in part to monitor the interference between the substrate and overlayer diffraction in the XSW and TCD spectra. This x-ray analog of reflection high energy electron diffraction oscillations will be analyzed theoretically using appropriate computational models.
